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Theses

Modélisation du couplage carbonatation – chlorures et étude multiéchelle de l’influence des granulats sur la diffusivité dans les bétons

Abstract : The corrosion of steels is one of the principal causes of degradation of reinforced concrete structures, especially in front of the sea. This degradation is due to the diffusion of chloride ions that can occur in the structures immersed in the seawater, those undergoing tidal cycles and also those subjected to the sea spray. The corrosion can also be due to the carbonation process of the concrete, which is responsible for decreasing of the pH and consequently the depassivation of the steels. This thesis proposes a physicochemical model to describe the penetration of aggressive agents in the first period of steel corrosion. This so-called « incubation » period corresponds to the period during which the transfer of aggressive species occurs in the concrete. In order to clearly identify the transport parameters of thismacroscopic model, a multi-scale approach is implemented to consider the diffusion in concretes. This approach is based on taking into account the detailed description of the microstructure of the concrete (constituents and morphology) by upscaling methods. This multi-scale approach is intended to be the most comprehensive with the consideration of the influence of the water-to-binder ratio of the cement paste, the properties of the aggregates and the transition zone between the cement paste and the aggregates. After identifying all the input parameters, the macroscopic physico-chemical model is used to evaluate the service life of a concrete subjected to coupling carbonation -chlorides in unsaturated medium. Following a validation of the model compared to experimental results, several applications of this model are presented.
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Submitted on : Monday, March 4, 2019 - 4:04:08 PM
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Mohamad Achour. Modélisation du couplage carbonatation – chlorures et étude multiéchelle de l’influence des granulats sur la diffusivité dans les bétons. Génie civil. École centrale de Nantes, 2018. Français. ⟨NNT : 2018ECDN0049⟩. ⟨tel-02056473⟩

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